CSS Customization

Theme CopilotKit components via CSS variables and class overrides.


/** * LangGraph TypeScript agent — CopilotKit showcase integration * * Defines a graph with a chat node and all showcase tools, * wired to CopilotKit via the sdk-js LangGraph adapter so frontend actions * and shared state flow seamlessly. */import { z } from "zod";import { RunnableConfig } from "@langchain/core/runnables";import { tool } from "@langchain/core/tools";import { ToolNode } from "@langchain/langgraph/prebuilt";import { AIMessage, SystemMessage } from "@langchain/core/messages";import {  MemorySaver,  START,  StateGraph,  Annotation,} from "@langchain/langgraph";import { ChatOpenAI } from "@langchain/openai";import { getA2UITools } from "@ag-ui/langgraph";import { makeChatOpenAI } from "./openai-headers";import {  convertActionsToDynamicStructuredTools,  CopilotKitStateAnnotation,} from "@copilotkit/sdk-js/langgraph";import {  getWeatherImpl,  queryDataImpl,  manageSalesTodosImpl,  getSalesTodosImpl,  scheduleMeetingImpl,  searchFlightsImpl,} from "../../shared-tools";// ---------------------------------------------------------------------------// 1. Agent state — extends CopilotKit state with a proverbs list// ---------------------------------------------------------------------------const AgentStateAnnotation = Annotation.Root({  ...CopilotKitStateAnnotation.spec,  proverbs: Annotation<string[]>,});export type AgentState = typeof AgentStateAnnotation.State;// ---------------------------------------------------------------------------// 2. Tools — shared implementations wrapped for LangChain// ---------------------------------------------------------------------------const getWeather = tool(  async ({ location }) => JSON.stringify(getWeatherImpl(location)),  {    name: "get_weather",    description: "Get current weather for a location",    schema: z.object({      location: z.string().describe("City name"),    }),  },);const queryData = tool(  async ({ query }) => JSON.stringify(queryDataImpl(query)),  {    name: "query_data",    description: "Query financial database for chart data",    schema: z.object({      query: z.string().describe("Natural language query"),    }),  },);const manageSalesTodos = tool(  async ({ todos }) => JSON.stringify(manageSalesTodosImpl(todos)),  {    name: "manage_sales_todos",    description: "Create or update the sales todo list",    schema: z.object({      todos: z        .array(          z.object({            id: z.string().optional(),            title: z.string(),            stage: z.string().optional(),            value: z.number().optional(),            dueDate: z.string().optional(),            assignee: z.string().optional(),            completed: z.boolean().optional(),          }),        )        .describe("Array of sales todo items"),    }),  },);const getSalesTodos = tool(  async ({ currentTodos }) => JSON.stringify(getSalesTodosImpl(currentTodos)),  {    name: "get_sales_todos",    description: "Get the current sales todo list",    schema: z.object({      currentTodos: z        .array(          z.object({            id: z.string().optional(),            title: z.string().optional(),            stage: z.string().optional(),            value: z.number().optional(),            dueDate: z.string().optional(),            assignee: z.string().optional(),            completed: z.boolean().optional(),          }),        )        .optional()        .nullable()        .describe("Current todos if any"),    }),  },);const scheduleMeeting = tool(  async ({ reason, durationMinutes }) =>    JSON.stringify(scheduleMeetingImpl(reason, durationMinutes)),  {    name: "schedule_meeting",    description: "Schedule a meeting (requires user approval via HITL)",    schema: z.object({      reason: z.string().describe("Reason for the meeting"),      durationMinutes: z.number().optional().describe("Duration in minutes"),    }),  },);const searchFlights = tool(  async ({ flights }) => JSON.stringify(searchFlightsImpl(flights)),  {    name: "search_flights",    description: "Search for available flights",    schema: z.object({      flights: z        .array(          z.object({            airline: z.string(),            airlineLogo: z.string().optional(),            flightNumber: z.string(),            origin: z.string(),            destination: z.string(),            date: z.string(),            departureTime: z.string(),            arrivalTime: z.string(),            duration: z.string(),            status: z.string(),            statusColor: z.string().optional(),            price: z.string(),            currency: z.string().optional(),          }),        )        .describe("Array of flight results"),    }),  },);// Dynamic A2UI via the canonical ag-ui factory (same as beautiful_chat /// a2ui_dynamic). A secondary LLM designs the surface; the factory forces the// host catalog and emits the a2ui_operations envelope. Replaces the prior// hand-rolled generate_a2ui tool.const generateA2ui = getA2UITools({  model: new ChatOpenAI({ model: "gpt-4.1" }),  defaultCatalogId: "copilotkit://app-dashboard-catalog",});const tools = [  getWeather,  queryData,  manageSalesTodos,  getSalesTodos,  scheduleMeeting,  searchFlights,  generateA2ui,];// ---------------------------------------------------------------------------// 3. Chat node — binds backend + frontend tools, invokes the model// ---------------------------------------------------------------------------async function chatNode(state: AgentState, config: RunnableConfig) {  const model = makeChatOpenAI(config, { temperature: 0, model: "gpt-4o" });  const modelWithTools = model.bindTools!([    ...convertActionsToDynamicStructuredTools(state.copilotkit?.actions ?? []),    ...tools,  ]);  const systemMessage = new SystemMessage({    content: `You are a helpful assistant. The current proverbs are ${JSON.stringify(state.proverbs)}.`,  });  const response = await modelWithTools.invoke(    [systemMessage, ...state.messages],    config,  );  return { messages: response };}// ---------------------------------------------------------------------------// 4. Routing — send tool calls to tool_node unless they're CopilotKit actions// ---------------------------------------------------------------------------function shouldContinue({ messages, copilotkit }: AgentState) {  const lastMessage = messages[messages.length - 1] as AIMessage;  if (lastMessage.tool_calls?.length) {    const actions = copilotkit?.actions;    const toolCallName = lastMessage.tool_calls![0].name;    if (!actions || actions.every((action) => action.name !== toolCallName)) {      return "tool_node";    }  }  return "__end__";}// ---------------------------------------------------------------------------// 5. Compile the graph// ---------------------------------------------------------------------------const workflow = new StateGraph(AgentStateAnnotation)  .addNode("chat_node", chatNode)  .addNode("tool_node", new ToolNode(tools))  .addEdge(START, "chat_node")  .addEdge("tool_node", "chat_node")  .addConditionalEdges("chat_node", shouldContinue as any);const memory = new MemorySaver();export const graph = workflow.compile({  checkpointer: memory,});

What is this?#

CopilotKit has a variety of ways to customize the colors and structure of the Copilot UI components via plain CSS. You can:

  • Override CopilotKit CSS variables to re-tint the whole UI
  • Target the built-in class names (.copilotKit...) for structural tweaks
  • Swap fonts per surface (messages, input, bubbles)
  • Replace icons and labels via component props

If you need to change behavior, not just look, see slots or fully headless UI.

Scoping the theme#

The demo keeps all of its styling in a sibling theme.css file and applies it only to the wrapper div holding <CopilotChat>. Importing the stylesheet from the page module is enough; Next.js bundles it with the route:

page.tsx
import "./theme.css";

Scoping every selector under a wrapper class keeps the overrides from leaking into the rest of the app.

CSS Variables (Easiest)#

The easiest way to change the colors used in the Copilot UI components is to override CopilotKit CSS variables. The demo sets them on the scope wrapper so they cascade into every nested chat component:

theme.css
/* HALCYON palette — a private library at golden hour. The whole theme is * one warm parchment hue, one warm ink, and a deep copper ember used * sparingly so it actually reads as a signal. */.chat-css-demo-scope {  --halcyon-paper: #f4efe6;  --halcyon-paper-soft: #ece6d9;  --halcyon-paper-elevated: #fbf8f2;  --halcyon-card: #ffffff;  --halcyon-rule: #d6cfbe;  --halcyon-rule-strong: #aea48a;  --halcyon-ink: #1a1714;  --halcyon-ink-soft: #3d362e;  --halcyon-ink-mute: #7a7468;  --halcyon-ember: #c44a1f;  --halcyon-ember-bright: #e45f2b;  --halcyon-ember-soft: #f3d7c5;  --halcyon-champagne: #98794a;  --halcyon-display:    "Instrument Serif", ui-serif, "Iowan Old Style", Georgia, serif;  --halcyon-serif:    "Fraunces", "Source Serif Pro", ui-serif, Georgia, "Times New Roman", serif;  --halcyon-sans:    "Inter Tight", ui-sans-serif, -apple-system, BlinkMacSystemFont, "Segoe UI",    sans-serif;  --halcyon-mono:    "JetBrains Mono", ui-monospace, "SF Mono", Menlo, Consolas, monospace;  --halcyon-shadow-soft:    0 1px 0 rgba(26, 23, 20, 0.04), 0 12px 32px -18px rgba(26, 23, 20, 0.18);  --halcyon-shadow-ember:    0 1px 0 rgba(196, 74, 31, 0.18), 0 14px 36px -16px rgba(196, 74, 31, 0.42);}

Once you've found the right variable, you can also apply the overrides inline via the CopilotKitCSSProperties helper:

import { CopilotKitCSSProperties } from "@copilotkit/react-ui";

<div
  style={
    {
      "--copilot-kit-primary-color": "#222222",
    } as CopilotKitCSSProperties
  }
>
  <CopilotSidebar />
</div>

Reference#

CSS VariableDescription
--copilot-kit-primary-colorMain brand/action color for buttons and interactive elements
--copilot-kit-contrast-colorColor that contrasts with primary, used for text on primary elements
--copilot-kit-background-colorMain page/container background color
--copilot-kit-secondary-colorSecondary background for cards, panels, and elevated surfaces
--copilot-kit-secondary-contrast-colorPrimary text color for main content
--copilot-kit-separator-colorBorder color for dividers and containers
--copilot-kit-muted-colorMuted color for disabled/inactive states
--copilot-kit-shadow-sm / -md / -lgElevation shadows for subtle surfaces, cards, and modals

Two token systems

The --copilot-kit-* variables above style the v1 component CSS (@copilotkit/react-ui). The newer v2 components (@copilotkit/react-core/v2) are Tailwind + shadcn-based and use a separate set of design tokens. See v2 design tokens below.

v2 Design Tokens (shadcn)#

The v2 components (@copilotkit/react-core/v2) ship a Tailwind v4 theme built on the standard shadcn/ui token set. Instead of the --copilot-kit-* variables, they read oklch color tokens that are scoped to the [data-copilotkit] root and wired into Tailwind utilities through an @theme inline block. This means you can re-skin the entire v2 UI by overriding a handful of CSS custom properties. Every component picks the change up automatically.

Override them on the [data-copilotkit] element (or any ancestor) the same way you would in a shadcn project:

globals.css
[data-copilotkit] {
  --primary: oklch(0.55 0.22 264); /* accent / action color */
  --primary-foreground: oklch(0.99 0 0); /* text on primary */
  --background: oklch(1 0 0); /* surface background */
  --foreground: oklch(0.145 0 0); /* primary text */
  --muted: oklch(0.97 0 0); /* subtle backgrounds */
  --border: oklch(0.922 0 0); /* dividers, outlines */
  --radius: 0.625rem; /* global corner radius */
}

/* Dark mode is keyed off a `.dark` ancestor */
.dark [data-copilotkit] {
  --background: oklch(0.145 0 0);
  --foreground: oklch(0.985 0 0);
  --border: oklch(0.269 0 0);
}

Reference#

These are the most commonly overridden v2 tokens. Each light value has a matching dark-mode value under .dark [data-copilotkit]. The full set (popover, accent, destructive, chart, and sidebar variants) lives in @copilotkit/react-core/v2/styles.css.

TokenDescription
--background / --foregroundBase surface background and primary text color
--primary / --primary-foregroundAccent/action color and the text rendered on top of it
--secondary / --secondary-foregroundSecondary surfaces (cards, panels) and their text
--muted / --muted-foregroundSubtle backgrounds and de-emphasized text
--accent / --accent-foregroundHover/active states and their text
--border / --input / --ringDivider/outline color, input borders, focus ring
--destructive / --destructive-foregroundError/danger color and its text
--card / --popover (+ -foreground)Elevated surface backgrounds and their text
--sidebar-*The sidebar's own background/foreground/border/ring set
--radiusBase corner radius; --radius-sm/md/lg/xl derive from it

oklch values

v2 tokens use the oklch() color space, which keeps perceived lightness consistent across hues. You can still pass hsl(), rgb(), or hex; any valid CSS color works.

Custom CSS#

The CopilotKit CSS is structured to allow customization via CSS classes. You can target specific pieces of the UI from your own stylesheet:

globals.css
.copilotKitButton {
  border-radius: 0;
}

.copilotKitMessages {
  padding: 2rem;
}

.copilotKitUserMessage {
  background: #007AFF;
}

The demo's theme.css wraps every selector under .chat-css-demo-scope so the overrides don't leak out. Here's the user message bubble block from that file:

theme.css
/* User message — a "transmission" in JetBrains Mono on a paper card. The * outer wrapper is the right-aligning flex column; we leave it transparent * and style the inner bubble (which uses cpk:bg-muted, hence we also * target the substring class as a stable hook). */.chat-css-demo-scope .copilotKitMessage.copilotKitUserMessage {  background: transparent;  padding: 0;  border: none;  box-shadow: none;}.chat-css-demo-scope  .copilotKitMessage.copilotKitUserMessage  > [class*="bg-muted"] {  font-family: var(--halcyon-mono);  font-size: 0.875rem;  font-weight: 400;  color: var(--halcyon-ink);  background: var(--halcyon-paper-elevated);  border: 1px solid var(--halcyon-rule);  border-left: 2px solid var(--halcyon-ember);  border-radius: 0;  padding: 12px 16px 12px 18px;  letter-spacing: -0.005em;  line-height: 1.55;  box-shadow: 0 1px 0 rgba(26, 23, 20, 0.03);  position: relative;}/* A mono "→" marker before the user's text to read like a CLI prompt. */.chat-css-demo-scope  .copilotKitMessage.copilotKitUserMessage  > [class*="bg-muted"]::before {  content: "→";  display: inline-block;  margin-right: 10px;  color: var(--halcyon-ember);  font-weight: 500;}

Reference#

CSS ClassDescription
.copilotKitMessagesMain container for all chat messages
.copilotKitMessageBase class applied to every message bubble (user and assistant)
.copilotKitInputText input container with typing area and send button
.copilotKitUserMessageStyling for user messages
.copilotKitAssistantMessageStyling for AI responses
.copilotKitHeaderTop bar of chat window containing title and controls
.copilotKitButtonPrimary chat toggle button
.copilotKitWindowRoot container defining overall chat window dimensions
.copilotKitMarkdownStyles for rendered markdown content
.copilotKitCodeBlockCode snippet container with syntax highlighting
.copilotKitSidebarStyles for sidebar chat mode
.copilotKitPopupStyles for popup chat mode

Custom Fonts#

You can customize the fonts by updating the fontFamily property on the relevant CopilotKit classes:

globals.css
.copilotKitMessages {
  font-family: "Arial, sans-serif";
}

.copilotKitInput {
  font-family: "Arial, sans-serif";
}

Custom Icons#

Customize icons by passing the icons prop to CopilotSidebar, CopilotPopup, or CopilotChat:

<CopilotChat
  icons={{
    openIcon: <YourOpenIconComponent />,
    closeIcon: <YourCloseIconComponent />,
  }}
/>

Custom Labels#

Customize all user-facing copy via the labels prop:

<CopilotChat
  labels={{
    welcomeMessageText: "Hello! How can I help you today?",
    modalHeaderTitle: "My Copilot",
    chatInputPlaceholder: "Ask me anything!",
  }}
/>